A woman who killed her co-worker in an upscale suburban Washington yoga clothing shop was convicted of first-degree murder Wednesday and faces the chance of life in prison.

ROCKVILLE, Md. – A woman who killed her co-worker in an upscale suburban Washington yoga clothing shop was convicted of first-degree murder Wednesday and faces life in prison.

The Montgomery County jury deliberated about an hour before returning the verdict against Brittany Norwood.

Norwood killed Jayna Murray inside the Lululemon Athletica shop in Bethesda on the night of March 11. Prosecutors said Norwood used at least a half-dozen weapons inside the store to kill Murray, then lied and told police that they had been attacked by masked men.

Norwood's lawyer conceded that Norwood killed Murray. But he said it happened during a fight and wasn't premeditated. The argument was aimed at sparing Norwood a first-degree murder conviction, which can carry a sentence of life in prison without parole.

Murray's family choked back tears as the verdict was read and a "yes" sounded from their side of the courtroom. Norwood and her family sat impassively and declined to comment afterward.

Norwood's attorney Doug Wood said she was disappointed at the speed of the verdict.

"I think that we were surprised that this happened so quick. I thought we had established a pretty good case for second-degree murder."

State's Attorney John McCarthy told jurors during closing arguments that there was abundant evidence of premeditation. He said Norwood lured Murray back to the store after closing by saying she had forgotten her wallet and needed to get back inside.

A medical examiner, Mary Ripple, testified that she found at least 331 wounds on Murray's body and that the woman was alive during the duration of the attack.